How Trailer Towing Regulations Work

Trailer Towing Laws by State

When you take a road trip in the U.S., you may cross multiple states. Although you may be a law-abiding tower in one state, you could be breaking trailer towing laws in another.

For instance, if you cross over from Alabama to Mississippi, you could suddenly be exceeding the maximum towing speed, which falls 10 mph (16 kph). Your trailer could be too wide -- as maximum width narrows by a six inches (15 centimeters) -- and you could suddenly need trailer brakes -- because the weight limit falls 1000 pounds [source: Bayliner.com]. In addition, states differ on their rules about multiple trailers. If you're hauling a camper and a Jet Ski behind it, you'd be OK in South Carolina, but breaking the law once you cross the Georgia state line.

Obviously, the laws for towing trailers can get confusing, so we'll break them down. First, let's get the bare necessities out of the way. No matter where you are in the U.S., you'll have to make sure the trailer you're towing is equipped with:

License plate light: Make sure to clearly display your license plate with its own light.

There's also equipment that, aside from being common sense to have for safety, is also required in the vast majority of states:

Safety chains: These chains, which cross over in the shape of an X to connect the trailer to the towing vehicle, help prevent separation if the hitch connection fails.

Brake lights: Your trailer isn't transparent. The people behind you are already having enough trouble seeing around your trailer for stops ahead, so the trailer should have brake lights of its own to prevent a rear-end collision.

Clearance lights: These might be required only if your trailer exceeds a certain width.

Reflectors: These are an invaluable precaution to keep your large trailer visible.

The following is extra safety equipment that some states require:

Breakaway brakes: Like safety chains, these prevent accidents when your hitch fails. These are power brakes that apply to the trailer upon separation from the tow vehicle.

Flares: Keep these at hand to clear off a section of the road after an accident.

Tie-downs: If you are loading anything on a trailer that could possibly fall off, you'll need tie-downs to secure it at multiple angles.

Luis Castaneda Inc./The Image Bank/Getty ImagesBe careful at high speeds -- braking takes a lot more space when you are towing a heavy trailer. This is why all states have a maximum towing speed, which may be lower than the posted speed limit.

Improper braking is one of the biggest mistakes to make while towing. It's also the easiest for those unused to hauling such weight. The more weight you are pulling, the more momentum you have, and the longer distance it will take to stop. This is why most states require towers to get trailer brakes when their rig exceeds a certain weight limit, sometimes as low as 1,500 pounds (680 kilograms). Braking is also more dangerous as speed increases, so all states stipulate a max towing speed, which can be as low as 45 mph (72 kph).

As we saw in the earlier example, there are also some important differences in dimension requirements among trailer towing laws by state. For instance, the trailer typically must be as narrow as 8 or 8 1/2 feet. The length of the entire rig could be restricted, sometimes as low as 53 feet (16 meters). Or the trailer itself may not be longer than 35 feet (10.7 meters) in some places. The height is often capped at 12 to 14 feet (3.7 to 4.3 meters).

If you do end up in an accident, you'll want to be insured. So next we'll talk about trailer towing insurance.